Treatment of leather



Patented June 16, 1936 UNITED STATES PATEN'l OFFICE TREATMENT OF LEATHER Henry Alfred Piggott and George Stuart James White, Blackley, Manchester, England, assignors to Imperial Chemical Industries Limited, Westminster, England No Drawing. Application May 8, 1934, Serial No. 724,631. In Great Britain May 13, 1933 7Claims.

' quaternary ammonium, quaternary phosphonium and sulphonium salts containing an allphatic chain of not less than 10 carbon atoms.

The alteration in properties depends to some extent on the means by which the leather is 0 treated with the solution. When the solution is brought into contact with the leather by spraying, stencilling, printingor like means, the treated portion generally shows much less aflinity for the dyestuff, while in some cases it shows negligible aflinity. When the solution is brought into contact with the leather by an immersing operation, for instance by a drumming, the leather may show an increased aflinity' for the dyestufi. Ac-

cording to either way of bringing the solution into contact the treated leather may take up the colour to a different hue.

Nigrosine G (Colour Index No. 865), Naphthalene black 123 (Colour Index No. 246) Lissamine green SF (Colour Index No. 670) are dyestufls for which the leather shows markedly less aferation; Naphthalene orange G (Colour Index No. 27), Crocein scarlet 33 (Colour Index No.

252), and Tartrazine N (Colour Index No. 640) are dyestuffs for which the treated leather shows only slightly less aflinity when treated by the same operation. The behaviour of any particular dyestufl can be easily ascertained by applying a solution of the colour to a test portion of leather, part of which has been suitably pre-treated with the quaternary salt.

According to the present invention we obtain new and valuable colour eil'ects on'leather by treating the leather with an aqueous solution of 40 a tchosen from the group consisting of quaternary ammonium, quaternary phosphonium salt and -sulphoniurn salts containing an aliphatic chain of not less than- 10 atoms of carbon and then colouring with an aqueous solution of a dyestuil. Suitable dyestuffs are acid, basic and direct dyestufls. The leather may be pretreated in parts only with .the salt. The aliphatic chains in the salm may be unsaturated.

Examples of suitable quaternary ammonium salts arez-dodecyltrimethylamnionium chloride (from dodecylchloride and .trimethylamine) cetyltrimethylammonium chloride, octadecylpyridinium iodide (see B. P. 379,396) ,stearylpyridinium bromide (see B. P. 379,396), stearamidofinity when treated by the spraying type of op-' (made by condensing asymmetrical dimethylp-phehylenediamine with stearoyl chloride and then treating the condensation product with dimethyl sulphate), and methylcetyl piperidinium methyl sulphate (made by interacting 2 molecules of piperidine with 1 molecule of cetyl bromide, separating the cetyl piperidine and treating with dimethyl sulphate).

Examples of suitable quaternary phosphonium salts are cetyltrimethylphosphonium bromide (made by interacting trimethylphosphine and cetyl bromide), and dodecyltrimethylphosphonium bromide (similarly made from dodecyl'bromide and trimethylphosphine) Examples of suitable sulphonium salts are cetyldimethylsulphonium methyl sulphate (made by heating cetylmethyl sulphide with vdlrnethyl sulphate; cetylmethyl sulphide is itself made by interacting equivalent quantities of cetyl mercaptan and dimethyl sulphate), benzylcetyl methylsulphonium methyl sulphate (made as hereinafter described), dodecyldimethylsulphonium bromide (made by heating dodecylmethyl sulphide with methyl bromide until a completely water-soluble product is obtained; dodecyl methyl sulphide is itself made by interacting equivalent quantities of dodecyl mercaptan and dimethyl sulphate in aqueous alkaline medium.

Cetylmethylbenzylsulphonium methyl sulphate is made as follows-1000 parts of cetylmercaptan are treated with 85 parts of sodium in methanol and then heated for 1 hour at about 80 C. with 470 parts of benzyl chloride. The product is poured into water, extracted with ether, the

ethereal layer distilled, and the fraction B. P. 250-260" 0/40 mm. collected. 100 parts of this cetylbenzyl sulphide are heated with 37 parts of dimethyl sulphate at about 80 C. for about 9 hour and then cooled when the cetylbenzylmethyisulphonium methyl sulphate crystallizes.

In carrying the invention into practical eflect very diverse methods may be used. Thus leather may be sprayed, stencllled or printed with an aqueous solution of the salt, then dyed by brushing, spraying, immersing or over-printing with either a solution of an individual dyestufl. or a mixture oi dyestuffs, especially interesting effectsbeing obtained by using dyestuffs for which the treated leather shows diflerent aflinities as described above. In the pre-treating of suede leathers the salt is applied as a cold or warm aqueous solution by immersing the leather; this is followed by a rinsing with cold water and dyeing in the usual manner with the dyestuff.

The invention is illustrated but not limited by the following examples, in which the parts are by weight.

Example 1.--Dry shivers (Sumac grain sheepskin splits are sprinkled with a 1% solution of stearylpyridinium bromide. Whenthe spots are dry the leathers are dyed by immersion in a water are spray-stcncilled with a 1% solution of tri-- methylcetyl ammonium chloride and dried. The leather is then sprayed with a solution of Cardinal red S (Colour Index No. 176) and dried and finished in the usual manner. The skins show orange spots on a brown ground.

Example 3.-100 lbs. dry semichrome Persian suedes are treated by immersion for 30 minutes in a solution of 1%-octadecylpyridinium iodide in 10 gallons of water circulating in a drum.

The leathers are then rinsed with cold water for 10 minutes and drummed in a warm solution of 4% Lissamine green SF (Colour Index No. 670) calculated on the weight of the leather. After rinsing, iat liquoring and drying out in the usual manner, the shade on the suede side is found to be much stronger than that obtained without the rare-treatment. v

Example 4.--A solution of 1 part of cetyldimethylsulphonium methyl sulphate in 100 parts of water is spotted on to East Indian tanned sheepskins. The skins are dried, immersed for about half a minute at C. in a 1% aqueous solution 01 Naphthalene black 123 (Colour Index No. 246) and rinsed in running water. A 'colouted pattern of light undyed spots on a dull blue ground is obtained.

Example 5.--1 part of dodecyldimethylsulphonium bromide and 1 part of Auramine 0 (Colour Index No. 655) are dissolved in parts of water. This solution is sprayed through stencils on to Sumac tanned grain sheepskin splits. The

skins are dried and dyed by immersion in a 1% solution of Methylene blue 23, (Colour Index No.

ammonium, quaternary phosphonium, and sulionium salts containing an aliphatic side chain 10 having not less than ten carbon atoms, and dyeing the leather with an aqueous solution of a dyestufl.

2. The process which comprises treating leather in part with an aqueous solution of a quaterl5 nary ammonium salt containing an aliphatic side chain having not less than ten carbon atoms, and dyeing the leather with an aqueous solution of a dyestufl.

3. The process which comprises treating leath- 20 er in part with an aqueous solution of a quaternary phosphonium salt containing an aliphatic side chain having not less than ten carbon atoms, and dyeing theleather with an aqueous solution oi! a dyestufi.

4. The process which comprises treating leather in part with an aqueous solution of a sulfonium salt containing an aliphatic side chain having not less than ten carbon atoms, and dyeing the leather with an aqueous solution or a dyestufl. v

5. The process which comprises treating leather in part with a cetyl trimethyl ammonium halide and dyeing the leather with an aqueous solution of a dyestufl.

6. The process which comprises treating leather in part with a cetyl trimethyl phosphonium halide, and dyeing the leather with an aqueous solution'ot a dyestufl.

7. The methodot dyeing leather which com- 40 prises treating leather in part with an aqueous solution of cetyldimethylsultonium methyl sulfate, and treating the leather with an aqueous solution of a dyestuil.

HENRY AIE'RED PIGGO'IT. GEORGE STUART JAMES WHITE. 

